The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In general, a hybrid vehicle uses an engine and a motor powered by a battery, as power sources thereof, and is controlled to allow the two power sources to operate in an area in which they can exhibit their individual characteristics according to driving conditions, so that the vehicle can be driven with the highest fuel efficiency.
Further, during its deceleration, the hybrid vehicle can collect an electrical energy converted from kinetic energy, which can achieve a higher fuel efficiency in comparison with a conventional gasoline-powered vehicle. Also, the hybrid vehicle can travel with its engine turned off in an urban area and can be thus used as an environment-friendly vehicle.
A hybrid vehicle is equipped with a Hybrid Control Unit (HCU), which is a high-level controller for controlling the overall operation of the vehicle, and controllers for individual devices constituting a system, and the controllers are connected through a network with the HCU, serving as the center thereof, to carry out cooperative control through information exchange therebetween.
The hybrid vehicle has an engine clutch mounted between an engine and a motor to connect the output torque of the engine, instead of a torque converter, in order to accomplish a cost reduction and minimize a loss of torque transmitted to a transmission, and is provided with an Electric Oil Pump (EOP) that supplies the hydraulic pressure in order to operate the engine clutch and the transmission.
The Electric Oil Pump (EOP) operates in conjunction with a Mechanical Oil Pump (MOP) provided in the automatic transmission to supply the hydraulic pressure necessary for the operation of the transmission, and is controlled according to interworking between the HCU and the Oil Pump Unit (OPU), which are connected with each other through the network.
For example, when the HCU provides the OPU with a target RPM of the oil pump that is determined based on the vehicle's state, a driver's demand, and information about the transmission gear position provided by a Transmission Control Unit (TCU), the OPU controls the supply of current to the electric oil pump according to the information provided by the HCU to operate the electric oil pump at the target RPM, thereby supplying the hydraulic pressure to operate the engine clutch and the transmission.
In this case, the HCU and the OPU exchange information through the network, such as the target RMP and the actual RPM of the oil pump, the operating state of the pump, whether there is an abnormality in the pump (normal or abnormal), etc.
Meanwhile, since the Mechanical Oil Pump (MOP) is operated by the driving force of the engine and the motor, the MOP acts as an element that disturbs the driving of the vehicle, which causes a decrease in fuel efficiency. Accordingly, in recent years, attempts to enhance fuel efficiency by forming hydraulic pressure using an Electric Oil Pump (EOP) only, without a Mechanical Oil Pump (MOP), have been increasing.
However, when the EOP is exclusively applied, there is no extra device capable of forming hydraulic pressure. Therefore, functions for continually measuring the performance of the OPU directly associated with the durability or function of the transmission and correctly controlling the vehicle when there is an abnormality in the OPU are required.
The description provided above as a related art of the present disclosure is only for helping understand the background of the present disclosure and should not be construed as being included in the related art known by those skilled in the art.